Laser controller

Abstract

A laser beam controller having a laser beam emitter for emitting a laser beam and a beam receiver which receives the laser beam emitted from the laser beam emitter and outputs a light receipt signal corresponding to a signal level of the laser beam. The laser controller includes a reference signal outputting device for outputting a reference signal in accordance with an environmental humidity of the laser controller. A comparator compares the light receipt signal of the light receiver with the references signal. A control device controls the output of the laser beam emitter in accordance with the comparison result of the comparator.

We claim: 
     
       1. A laser controller, comprising: means for emitting a laser beam;   means for receiving said laser beam emitted by said laser beam emitting means, said receiving means outputting a receipt signal that corresponds to a power level of said laser beam;   means for outputting a reference signal in accordance with an ambient humidity surrounding said laser controller;   means for comparing said receipt signal of said light receiving means with said reference signal; and   means for controlling an output of said laser beam emitting means in accordance with a comparison result of said comparing means.   
     
     
       2. The laser controller of claim 1, wherein said control means controls a power of said laser beam emitted by said laser beam emitting means so as to make said receipt signal of said receiving means coincidental with said reference signal. 
     
     
       3. The laser controller of claim 1, wherein said laser beam emitting means comprises a laser head having a laser diode and a driver that supplies said laser diode with electric current to drive said laser diode. 
     
     
       4. The laser controller of claim 2, wherein said control means varies said power of said laser beam emitted by said laser beam emitting means to make said receipt signal of said receiving means coincidental with said reference signal when said receipt signal of said receiving means is not identical to said reference signal. 
     
     
       5. The laser controller of claim 1, further comprising means for adjusting said output of said laser beam emitting means to a predetermined reference value that is dependent on a reference ambient humidity. 
     
     
       6. The laser controller of claim 5, wherein when an ambient condition shifts from said reference ambient humidity, said reference signal outputting means varies said reference signal in accordance with said shift in ambient condition. 
     
     
       7. The laser controller of claim 6, wherein said controlling means controls said output of said laser beam emitting means so as to make said receipt signal of said receiving means coincidental with said reference signal. 
     
     
       8. The laser controller of claim 7, wherein said controlling means controls said output of said laser beam emitting means prior to a commencement of a laser scanning. 
     
     
       9. The laser controller of claim 1, wherein said reference signal outputting means comprises a humidity sensor for detecting said ambient humidity surrounding said laser controller. 
     
     
       10. The laser controller of claim 9, wherein said reference signal outputting means outputs a reference signal that corresponds to said ambient humidity detected by said humidity sensor. 
     
     
       11. The laser controller of claim 10, wherein said reference signal outputting means outputs reference signals to vary a power level of said laser beam when said ambient humidity detected by said humidity sensor varies from a predetermined reference value. 
     
     
       12. The laser controller of claim 11, wherein said comparing means comprises a comparator to which said reference signal and said receipt signal are inputted. 
     
     
       13. The laser controller of claim 12, wherein said reference signal outputting means outputs said reference signal to vary said power level of said laser beam when said ambient humidity detected by said humidity sensor is higher than said predetermined reference value, and wherein said controlling means increases said power level of said laser beam emitting means until an output of said comparator is inverted. 
     
     
       14. The laser controller of claim 13, wherein said reference signal outputting means outputs said reference signal to decrease said power level of said laser beam when said ambient humidity detected by said humidity sensor is lower than said predetermined reference value, and wherein said controlling means decreases said power level of said laser beam emitting means until an output of said comparator is inverted. 
     
     
       15. An apparatus for controlling an electrophotographic device, comprising: a laser that emits a beam of light;   a photodetector that detects said emitted light beam to obtain a power signal related to a power level of said emitted light beam;   a humidity sensor that determines an ambient humidity surrounding said laser to obtain a reference signal;   a comparator that compares said reference signal to said power signal; and   a controller that controls said power level of said emitted light beam based upon a comparison result of said comparator.   
     
     
       16. The apparatus of claim 15, wherein said reference signal varies in accordance with said ambient humidity determined by said humidity sensor. 
     
     
       17. An apparatus for controlling a printing density of an electrophotographic device, comprising: a laser that emits a beam of light;   means for detecting a power level of said emitted beam of light;   means for setting a reference signal;   a comparator that compares said reference signal to said detected power level; and   a controller that controls said power level of said emitted light beam based upon a comparison result of said comparator to control a print density of said electrophotographic device, wherein said reference signal setting means comprises a humidity sensor that varies said reference signal based upon a detection of an ambient humidity surrounding said laser.